Type belt device



Dec. 10, 1963 v. R. SIMPSON TYPE BELT DEVICE 2 Sheets-Sheet 1 Filed Dec. 22, 1961 //vi//v 70/? =XVIICTOR R. SIMPSON gzozyjd FIG. 1

Dec. 10, 1963 v. R. SIMPSON 3,113,509

' TYPE BELT DEVICE Filed Dec. 22, 1961 2 Sheets-Sheet 2 United States Patent Ofiice 3,ll3,59 Patented Dec. 10, 1963 3,113,509 TYPE BELT DEVECE Victor R. Simpson, flwego, N.Y., assignor to International Business Machines Corporation, New York, N.Y., corporation of New York Filed Dec. 22, 1961, Ser. No. 161,62tl 3 Claims. (1. 101111) This invention relates to a printing mechanism and more particularly to an improved type belt suitable for use in high speed printing apparatus.

While not limited thereto, the type belt of the present invention has particular utility in an on-the-fly print apparatus of the type sometimes referred to as a chain printer, embodiments of which are shown and described in US. Patent 2,918,865 issued to E. R. Wooding on December 29, 1959, and U.S. Patent 2,993,437 issued to F. M. Demer and E. l. Grenchus on July 25, 1961.

in printing apparatus of the type disclosed in the abovementioned patents, the printing mechanism comprises a chain of type members uniformly spaced, means for moving the type chain in a continuous path at a constant speed, and a plurality of hammers located on a print line portion of said path, said hammers being selectively operable to strike a print medium against the type members as they align with various hammers.

In a copending application of V. R. Simpson and T. W. Thompson, Serial No. 1,761 filed January 11, 1960, now U.S. Patent 3,041,964, a continuous type belt is shown for use in a chain printer of the type described in the above references. The type belt of said copending application comprises a composite belt member to which type members are removably attachable. The belt member comprises an inner thin band of flexible sheet steel coated with a uniform layer of plastic material bonded to the surface of the steel band. In the type belt of the copending application, the fixation of the type members is performed by clamping interconnectable type member body elements to the composite belt member. In order that the type members retain a fixed position relative to each other and a fixed alignment relative to the belt member, the clamping must be performed at such a rate that substantial stress is placed on the external coating. Such clamping action tends to reduce the thickness of the plastic coating in the area where maximum thickness is desired. In addition, the fixation of the type members in such an arrangement as shown in the copending application depends substantially primarily on friction that exists between the type member and the plastic coating and to some extent on the slight deformation of the plastic coat- 1112.

It is a general object of the present invention to provide a type belt which is an improvement of the type belt of said above-mentioned application.

It is a specific object of the present invention to provide an improved construction of type and belt members whereby the type members are more reliably positionable on the belt member.

it is a further object of the present invention to attain the preceding specific object without afiecting the removability of type members for replacement or the like.

It is a further object of this invention to attain the above objects while enhancing the effectiveness of the coating for the tension member of the belt member to absorb impact energies and compressive forces which otherwise tend to foster rupture of the type belt.

The above and other objects are attained in accordance with the practice of the present invention by providing the plastic coating of the composite belt member with detent means for each of the removably attachable type members of the type belt. In the preferred embodiment the detent means takes the form of integral raised extrusions on the surface of the plastic coating, and the type members have recesses adapted to receive the extrusions. The extrusions preferably have a shape and form which cooperating with surfaces defining the recesses in the type members produce a locking of the type member to the belt member against lateral displacement and twisting misalignment.

In accordance with another feature of this invention, the detents are formed in the coating of the belt member by the type member. For that purpose the type member has recesses formed in the clamping surface. The process of forming the detents comprises clamping the type members to the belt member such that the grooved clamping surface compresses the coating without distortion. After the type members are clamped to the composite belt member, the assembly is heated to stress relieve the coating. The pressure of the type member upon the heated coating extrudes portions thereof in contact with the clamping surface into the grooves. The type chain assembly is then cooled. When cooled, the type chain is usable in a printer. In the extrusion process, a bond is not formed so that the type member may be removed by unclamping. With the detent permanently fixed, a like type member may be assembled to the same positions in the chain. By precision controlling of the manufacture of type members and location of grooves, and due to the fixed position of the detents, new type members may be added to the type chain in proper position and alignment. Thus an improved type chain has been provided which is relatively simple in construction and which is useful for obtaining improved printing quality for on-the-fiy printers. Also by such a construction where a plurality of type members are to be removably attached to the belt member, the type members need not be abutted to obtain secure positioning with accuracy.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawings.

In the drawings:

FIG. 1 is an isometric view of a schematic version of an on-thefiy chain printer in which the present invention has particular utility.

FIG. 2 is an exploded isometric view showing an engraved metal type member suitable for removable attachment to a flexible type belt carrier.

FIG. 3 is a cross section showing a type member of FIG. 2 attached to a flexible belt type carrier.

FIG. 4 is a transverse cross section of a belt member of the type used in the assembly of FIG. 3.

FIG. 5 is a second cross sectional view showing the type member of FIG. 2 assembled to a flexible belt type carrier.

FIG. 6 is a cross sectional view of the assembly taken along the line 66 in FIG. 5.

FIG. 7 is a fragment of a type carrier belt member of the type shown in FIGS. l6 taken in isometric view to illustrate the general'construction thereof.

Referring to the drawings, a preferred form of printer is shown in FIG. 1 comprising an endless type chain or type belt it supported on spaced-apart sprocket wheel 11 and idler pulley 12. Type belt it? carries a plurality of uniformly spaced type members 13 clamped to a continuous belt member 14. The type members 13 may be any number of a set of a predetermined number of type characters arranged in a predetermined sequence and uni formly spaced along the type belt to completely fill the same. The sprocket wheel 11 is adapted to be driven preferably at a constant speed by motor means (not shown) through shaft or the like to move the belt transversely across a record strip 16.

The record strip which is adapted to pass over and the guide members 17 and 18, respectively may be advanced step by step by conventional means including lower and upper sprocket wheels 19 and 2t respectively. T he wheels 15? and 24 may be mechanically coupled through pulleys 21 by suitable means such as a drive belt (not shown) adapted to drive them in a synchronous manner.

Printing of the characters represented by the type members 13 on record strips 16 is accomplished by a plurality of type hammers 22 which in the printer shown strike the type members while they are in motion. The hammers 22 are mounted horizontally on vertical leaf springs 23 anchored in a horizontal base member 24. The hammers 22 are normally biased by the springs 23 out of engagement with the record strips 16 and are adapted to be individually actuated by electromagnets 25 having armatures 26 pivotally mounted on shaft 27. Upon the actuation of any hammer 22, it strikes a type member 13 of the type belt 19 so that the corresponding character is printed on the record strip through an ink ribbon 23 supported by supply and take-up spools 29 and 30, respectively. A guide member 31 is provided to guide the type members 13 and to provide impact resistance therefor. The guide member itself may have shock absorbing properties to further enhance the life expectancy of the type belt and associated components.

The type carried by the type members may be desirably spaced apart further than the hammers, the ratio of the type spacing to hammer spacing being sufiicient to insure that type members are in alignment with spacedapart hammers at any one instant. A further illustration of this principle of spacing may be understood by reference to US. Patent 2,993,437 issued on July 25, 1961, to F. M. Demer and E. J. Grenchus.

As set forth in the previously mentioned copending application of V. R. Simpson and T. W. Thompson the resistance to rupture of the type belt llil is obtained by providing a composite belt member 14. A composite belt member is shown more clearly in FIGS. 3, 4, and 7, and comprises an inner tension member 32 having an outer plastic coating 33 bonded to the surface thereof. In the preferred embodiment the tension member 32 is a thin flexible strip of high tensile strength, high modulus elasticity steel. A particular example of a suitable material for a tension member is the chrome nickel alloy steel commonly referred to as stainless steel. Also suitable are cobalt, nickel base alloys of the type marketable under the trade names of Dynavar and Elgiloy.

Further in the preferred embodiment, the plastic coating 33 is either a polyester film or nylon. An example of a suitable polyester film was found to be polyethylene terephthalate, types of which are marketable under the trademark Mylar and the trade name Videne. Examples of nylon found suitable as a plastic coating 33 for the purposes of the present invention were the linear polyamides of low molecular weight marketable under the trademark designations Zytel 61 and Zytel 63. Further information concerning the manner in which the composite belt member is manufactured may be obtained by referring to the above-mentioned copending application of Simpson and Thompson.

In accordance with this invention the type members 13 are individually removably attachable to band member 14-. In the preferred embodiment, the removable attachment of the type members 13, shown in detail in FIGS. 2, 3, 5, and 6 is achieved by providing that each type member comprise a type block member 34 and a clamping member 35. The type block member 34 has a face on which type characters 36 are formed in a suitable manner such as by the well-known engraving techniques. Two extensions 37 and 38 projecting from the back side of block member 34- are spaced apart to form a band receiving groove 39. Grooves 4d and 41 in the upper and lower extensions, respectively, provide recesses d for the clamp member 35. Clamp member 35 is attached to the type block member 34 by screws 42 which are receivable in openings 43 and 44 provided for that purpose, the latter eing threaded.

While not necessarily limited thereto, the type block member 34 will comprise more than one spaced engraved type 36 which may be given a spacing characteristic relative to the hammer spacing in accordance with the principle previously discussed in connection with the U8. patent of Demer and Grenchus.

The attachment of the type members 13 to the band member is effected by lacing band 14 within central groove 39, placing the clamp member 35 in grooves 49 and 41 and then securing the same with screws 42 threaded through the openings 43 and 44.

In accordance with a feature of this invention, the type members 13 are removably attachable to the belt member 14 in such a manner that there is no displacement or misalignment. Furthermore, this is achieved without excessively compressing coating 33 which is bonded to tension member 32. This result is obtained by providing a positive interengagement between the type member 13 and coating 33 which counterbalances forces capable of displacing or misaligning the type members 13 along belt member 14. in the preferrd embodiment, retaining means is provided on the rear surface 34a of type block 3 5 which is capable of positively engaging layer 33a of coating 33. The preferred form of retaining means on type block 34 comprises one or more elongate grooves 34b. The grooves 34b, which are preferably rectangular in transverse cross section as shown in FIGS. 3 and 6 may be formed in the inner surface 34a of block 34 as part of the fabrication step which produces extensions 37 and 38 or they may be formed as a separate step in connection with the finishing process for type block 34. In either case, the grooves 34b can be formed with precision so that when type member 13 is clamped to belt 14, e.g., in a fixture a precise transverse alignment for positioning type faces 35 is obtained.

For engaging the type block 34 and retaining it in precise position on belt member 14, coating 33 is provided with detent means 33b formed in layer 33a of coating 33. The detent means 33b, in a manner corresponding with grooves 34b of type block 34, are elongate and more or less rectangular in cross section as shown in FIGS. 3, 6, and 7. Detent means 3311 are fiormed in layer 33a of coating 33 so as to be precisely transverse and preferably as an integral extension therefrom.

A method for producing a particularly precise formation of detents 331) on coating 33a so that precise location of type members 113 on belt 14 is obtained is as follows:

The various type members '13 are assembled to belt member 14 in the manner previously described. The screws 42. are tightened to cause bar 35 to compress layer 33a of coating 33 against surface 34a. At the time of attachment, the type members 13 are accurately positioned so that both vertical alignment of type faces 36 and position of type member 13 on belt member 14 is obtained. For this purpose, a fixture (not shown) is prefenably used. The screws 42 are tightened to provide a degree of clamping pressure on layer 33a. The pressure however, is not so great as to effect appreciable distontion of layer 33a into grooves 34b. With all the type members 13 clamped to belt 14, the assembly is then placed in an oven and heated. Heat is applied at a temperature and for a time to cause coating 33, particularly layer 33a, to become stress relieved. Under such circumstances, layer 33a vbeco-mes softened so that layer 33a can then be extruded into grooves 34b of type block 34. With the coating 33 in a stress relieved condition, the screws 42 are further tightened whereby layer 33a is extruded into grooves 34b forming the detent means 33b. The assembly is then removed from the furmace and allowed to cool. Type members 13 may be removed from the belt 14, leaving detents 33b formed in precise position on coating 33.

In the preferred embodiment it is preferable that the retain-ing of type members 13 be performed primarily through the detent means 3312. For that purpose coating 33 is made thicker in layer 33a. By making layer 33a thicker and keeping coating 33 much thinner on the opposite side of tension band 32, substantially no deformation takes place in the thin layer of coating 33 during the extrusion of detents 33b. Thus, the shock absorbing properties of coating 33 are not diminished. In addition, with substantially no deformation formed in the thinner layer of coating 33, the fabrication of type members 13 is facilitated, i.e., the precision fabrication is primarily emphasized in connection with block member 34 Whereas clamping member 35 need not be formed with as great precision.

While various materials may be used in practicing the present invention, a suitable type chain may be formed in accordance with the following specifications.

Tension member 32 is a strip of stainless steel .003 inch thick and .200 inch wide. Coating 33 is formed of two strips of plastic material such as nylon or Mylar where the layers are respectively .001 and .004 inch thick. The respective layers are Wide enough to be bonded to the sides and edges :of tension band 32. With grooves 34b formed .005 inch deep and .015 inch wide, the screws 42 are tightened to 18 inch-ounces of torque at the time of initial assembly and then retightened to the same level after the assembly is placed in an oven and heated to 240-270 F.

While the invention has been particularly shown and described with reference to :a preferred embodiment thereof, it will be understood by those skilled in the art that the foregoing and other changes in form and details may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. A type belt comprising in combination a flexible belt member comprising a flexible tension member enclosed within a shock energy absorbing coating bonded to the outer surface thereof, at least one type member removably attached to said belt member, and means for maintaining said type member at a fixed predetermined position on said belt member comprising raised detent means formed integral with said coating, and means formed in said type member for engaging said detent means and cooperable therewith to oppose displacement of said type member along said belt member.

2. A type belt in accordance with claim 1 in which said type member comprises first and second type member ele ments, said elements being interconnectable for clamping said type member to said belt member, one of said elements having a retaining igroove means formed in a surface engageable with said coating of said belt member, said groove means being formed for receiving said raised detent means of said coating and coactable therewith to oppose displacement of said type member along said belt member.

3. In a printer apparatus having a print mechanism comprising a plurality of type members, a plurality of hammer means selectively operable for striking said type members along a print line, means for moving said plumality of type members in a uniformly spaced manner along said print line and in a continuous path including a composite flexible belt member adapted to carry said plurality of type members, said type members being removably attachable to said belt member by compressive clamping action of members engageable with opposite surfaces of said belt member, said composite belt member comprising a tension band member and a shock energy absorbing coating bonded to the outer surface of said band member, said coating isolating said tension member from said type members, and means for maintaining said type members at plural uniformly spaced predetermined fixed positions on said belt member in opposition to displacement forces produced by the impact of said hammer means on said type members including plural raised detent means formed integral with said coating at said predetermined positions along said belt member for engaging said type members, and means formed in said type members for engaging said raised detent means and coacting therewith to hold said type members at said fixed positions in opposition to longitudinal displace ment forces produced by impact of said harrn'ner members and said type members.

References Cited in the file of this patent UNITED STATES PATENTS 2,267,661 Meyers Dec. 23, 1941 2,865,214 Runton Dec. 23, 1958 2,899,242 Bombardier Aug. 11, 1959 3,041,964 Simpson et a1. July 3, 196-2 3,041,965 Sasaki July 3, 1962 

1. A TYPE BELT COMPRISING IN COMBINATION A FLEXIBLE BELT MEMBER COMPRISING A FLEXIBLE TENSION MEMBER ENCLOSED WITHIN A SHOCK ENERGY ABSORBING COATING BONDED TO THE OUTER SURFACE THEREOF, AT LEAST ONE TYPE MEMBER REMOVABLY ATTACHED TO SAID BELT MEMBER, AND MEANS FOR MAINTAINING SAID TYPE MEMBER AT A FIXED PREDETERMINED POSITION ON SAID BELT MEMBER COMPRISING RAISED DETENT MEANS FORMED INTEGRAL WITH SAID COATING, AND MEANS FORMED IN SAID TYPE MEMBER FOR ENGAGING SAID DETENT MEANS AND COOPERABLE THEREWITH TO OPPOSE DISPLACEMENT OF SAID TYPE MEMBER ALONG SAID BELT MEMBER. 